We have previously hypothesized that enhanced sympathetic receptor sensitivity contributes to the etiology of type w diabetes mellitus (1). The goal of the present proposal is to plan a study to determine if non-diabetic Black females, known to be at high risk for developing type 2 diabetes, show increased glycemic reactivity to behavioral and neuroendocrine challenges affecting the sympathetic nervous system. Two specific sets of studies are proposed. First, we will study the differential effect of mental arithmetic task on glucose, insulin, glucagon, catecholamines and cortisol in obese and lean Black and White subjects. Data from these studies will allow us to determine if behavioral tasks differentially affect the metabolic responses of Black and White females and will suggest likely neuroendocrine mediators. Second, the differential glucose and insulin responses to adrenergic pharmacologic challenges which have been shown to differentiate normal individuals from diabetic patients and diabetes prone mice from diabetes resistant animals will be studied in both lean and obese Black and White subjects.